The first form of electric communication, dating back to the early 1840s, used an encoding and decoding scheme involving two binary elements—a long duration element and a short duration element. The longer was called a “dash” and the shorter was called a “dot.”
An alphabetic code was developed whereby the characters were associated with one or more elements in unique combinations. Similarly, the digits zero through nine were associated with unique element combinations. A message, for example, could then be converted into the equivalent of alphabetic characters whereby individual letters were separated from one another by leaving a short time interval or space, and words were distinguished from one another by leaving a longer time interval between the last character of a previous word and the first character of a following word.
Using a large switch, called a “key,” an operator could encode a message by closing then opening the key for short or long durations and allowing appropriate time intervals between characters and words. This was called “sending.” Another operator, upon hearing the encoded message's code elements could decode the message into the appropriate characters and words. This was called “copying.”
By the early twentieth century, a similar scheme was adopted for sending and copying wireless signals that were keyed into appropriate short and long duration elements.
Currently, thousands of wireless operators use Morse coded encoding and decoding on the high-frequency bands allocated to amateur radio operators, worldwide. As a result, there is a demand for tools and methods for learning to send and copy Morse code.
In the early- to mid-twentieth century, phonograph records and special tape recorders were used for teaching Morse copying. Sending was taught using interactive methods involving learners and instructors whereby learners would send and advisors would assess the accuracy.
Currently, the Internet serves as a medium for several tools that continue the training of Morse code copying. However, sending is still essentially learned by interaction with learners and instructors.